We’ve all seen thousands of banner adverts on the internet but can you remember the last one? Maybe, you can remember your favorite one that had a golf game in it but do you remember what brand it was for? Banner advertising is one of the earliest forms of advertising on the internet, so called because the adverts typically represented graphical banners across the page.

The sizes were defined by the Interactive Advertising Bureau (IAB) to commoditize the online advertising industry, taking adverts into a fixed set of sizes and styles similar to the 15 and 30 second ad slots on TV or 48 sheet posters. This makes it easier for sites to sell advertising and for advertisers to book using a clear set of sizes. Cost per Thousand impressions (CPM) is the normal unit of sales and is a cost for a thousand of the banner impressions to appear on a site, normally restricted to one per page. A few problems lay with the online formats, namely:

The various computer screen sizes and resolutions people use make one size banner appear at various different sizes and take up a different proportion of the screen for people with different screen resolutions. You can’t really imagine an advertiser in magazine being too happy about his full page advert appearing at smaller sizes in some magazines.

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